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Jastermereel
2009-06-23, 05:35 PM
I know that debating the physics of a role playing game kills catgirls, but this seems more blatant than the average nekocidal exploit.
I was reading through the DMG looking for rules for mobs and stumbled onto this tidbit from the section on rooftops:

Eventually a character runs out of roof, requiring a long jump across to the next roof or down to the ground. The distance to the next closest roof is usually 1d3x5 feet horizontally, but the roof across the gapy is equally likely to be 5 feet higher, 5 feet lower, or the same height. Use the guidelines on page 77 of the Player's Handbook (a horizontal jump's peak height is one-fourth of the horizontal distance) to determine whether a character can make the jump.
It's been a little while since my high-school (and college) classes covering Newtonian physics, so I could be completely wrong here, but, isn't a jump more or less a parabolic arc? Wouldn't the peak height of a long-jump be at exactly half the distance of the jump?

EDIT: Wow...I'm really feeling stupid now :redface:

Thank you all for pointing out the obvious. Please, feel free to NOT point it out further :smalltongue:

JMobius
2009-06-23, 05:38 PM
I think it means "the peak height will be 25% of the horizontal length", not "the peak height will be AT 25% of the horizontal distance"

Mando Knight
2009-06-23, 05:39 PM
Roughly. It would only be exact if you were jumping without any other forces other than gravity (i.e. air resistance) acting on you.

JMobius is correct about the interpretation of the text, though. You jump 1/4 as high as you travel horizontally, not "the peak of your jump is at 1/4 of the way through your jump."

Keld Denar
2009-06-23, 05:40 PM
You are correct, but thats not what that passage is stating. Its stating that the Ymax value is 1/4 of the value of the distance between X0 and X1. It would still be located at X2, which is X2 = (X1 - X0) /2.

Aris Katsaris
2009-06-23, 05:43 PM
Wouldn't the peak height of a long-jump be at exactly half the distance of the jump?

I don't think it says *where* the peak height is. It indicates how *much* it is.

So, if you leap 10 feet horizontally, the peak height of your jump will be 2.5 feet. (And located at the 5-foot point, but that's irrelevant).

Clementx
2009-06-23, 05:43 PM
It's been a little while since my high-school (and college) classes covering Newtonian physics, so I could be completely wrong here, but, isn't a jump more or less a parabolic arc? Wouldn't the peak height of a long-jump be at exactly half the distance of the jump?
If your line of motion was exactly at 45 degrees from the surface and your velocities were perfectly balanced, yes. Runners in practice have a lot of horizontal momentum, outweighing their vertical impulse. RAW, its close enough for most situations.

Btw, 1/4 height also creates a parabola. Just a flatter one.

Mando Knight
2009-06-23, 05:49 PM
If your line of motion was exactly at 45 degrees from the surface and your velocities were perfectly balanced, yes. Runners in practice have a lot of horizontal momentum, outweighing their vertical impulse. RAW, its close enough for most situations.

Btw, 1/4 height also creates a parabola. Just a flatter one.

You're misinterpreting the question. He interpreted the quote as stating that the peak of the jump occurs at 1/4 of the way through the jump, which is quite different from the height of the peak being 1/4 of the total horizontal distance jumped.

Jastermereel
2009-06-23, 06:20 PM
Wow...I'm really feeling stupid now :redface:

Thank you all for pointing out the obvious.

Keld Denar
2009-06-23, 07:04 PM
Its ok, we all make mistakes. Like me for example. I actually made a character who memorized Ray of Stupidity. Its ok, I got better.

Jastermereel
2009-06-23, 07:10 PM
Its ok, we all make mistakes. Like me for example. I actually made a character who memorized Ray of Stupidity. Its ok, I got better.

Wow. Now I don't feel so bad :smallwink:

Ironically, this thread jumped the shark before either the quarter- or half-way marks.

PairO'Dice Lost
2009-06-23, 10:39 PM
Wow. Now I don't feel so bad :smallwink:

Ironically, this thread jumped the shark before either the quarter- or half-way marks.

But was it jumping parabolically?